The present invention relates in general to combination locks for safes and the like and more particularly to such combination locks having additional locking means for preventing manipulation of the combination lock until a preliminary security lock release is effected.
Various types of combination locks have been developed heretofore such as in United States Letters Patent Nos. 3,981,167; 4,532,785; and 4,628,715 which includes a plurality of gated tumbler wheels within a lock housing which are manipulated through turning a dial exteriorly of the housing. When the gates of the tumbler wheels are aligned, an associated fence portion of a bolt release lever is allowed to move into engagement with a cam way of a dial associated cam means to allow movement of the bolt via the bolt release lever through continued rotation of the combination lock dial after entry of the combination via the dial. Other types of combination locks have also been developed heretofore, wherein a combination must be entered either by digital input to an electronic mechanism or the manipulation of a dial in order to move a bolt and/or bolt associated release lever to allow access to a safe or security space protected by the lock mechanism.
It would also be desirable to have an additional security lock associated with such combination locks in order that additional security controls may be afforded. For example, it would be desirable to have an alarm circuit associated with such locks provided so that on operation of a preliminary switch or lock mechanism, an alarm signal would be generated for noticing proposed entry to the security location or safe and it would be desirable to delay the actual manipulation of the combination lock by such authorized personnel until appropriate security personnel had an opportunity to take action with regard to the alarm signal. It would also be desirable to be able to record personal identification code numbers for authorized individuals who know the combination lock and access the safe or security space protected thereby. A record of such access by authorized individuals would also be desired so that security personnel could be aware of the times, dates and identification of individuals accessing the protected space.